This
article presents final technical and economical results of
the comprehensive control rehabilitation project done for the ammonia
synthesis plant at JP Nawozy, GA ZAK S.A. The project included the
following activities: review of the existing control philosophies
and instrumentation infrastructure, design and implementation of the
new control loop templates, and tuning of the revised controls over
the entire installation. These activities improved installation operation
with much more reliable and repeatable dynamic responses. Simultaneously,
the overall installation efficiency has been also increased. This
initiative is considered as the prerequisite for further control system
upgrade with use of advanced process control and process optimization.
Different variants for abatement of N2O emission from nitric acid plants with the use of catalysts developed at Łukasiewicz-INS were analyzed. Activity tests on a pilot scale confirmed the high activity of the studied catalysts. A two-stage catalytic abatement of N2O emission in nitric acid plants was proposed: by high-temperature decomposition in the nitrous gases stream (HT-deN2O) and low-temperature decomposition in the tail gas stream (LT-deN2O). The selection of the optimal variant for abatement of N2O emission depends on the individual characteristics of the nitric acid plant: ammonia oxidation parameters, construction of ammonia oxidation reactor and temperature of the tail gas upstream of the expansion turbine. It was shown that the combination of both deN2O technologies, taking into account their technological constraints (dimensions of the catalyst bed), allows for a greater abatement of N2O emission, than the use of only one technology. This solution may be economically advantageous regarding the high prices of CO2 emission allowances.
This article describes the influence of various design modifications of the ammonia oxidation reactor operating in nitric acid plant TKIV in Kędzierzyn-Koźle on flow distribution of an air-ammonia mixture. The CFD (Computational Fluid Dynamics) simulations of turbulent flow were carried out with SST k-ω turbulence model to close the system of RANS (Reynolds Averaged Navier-Stokes) equations. The simulation results show that the properly selected perforated plate screen and the conical diffuser ensure uniform flow of gas on the ammonia oxidation catalysts and on the catalysts for nitrous oxide decomposition. It was proved experimentally achieving uniform temperature of nitrous gases in different locations under the catalytic gauzes and high efficiency of ammonia oxidation and nitrous oxide decomposition
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